POWER LOSS (W) LTC3736-2 TM Dual 2-Phase, No R , SENSE Synchronous Controller with Output Tracking FEATURES DESCRIPTION n No Current Sense Resistors Required The LTC 3736-2 is a 2-phase dual synchronous step-down n Out-of-Phase Controllers Reduce Required switching regulator controller with tracking that drives Input Capacitance external complementary power MOSFETs using few ex- n Tracking Function ternal components. The constant-frequency current mode n Wide V Range: 2.75V to 9.8V architecture with MOSFET V sensing eliminates the need IN DS n 0.6V 1% Voltage Reference for sense resistors and improves ef ciency. Power loss and n High Current Limit noise due to the ESR of the input capacitance are minimized n Constant-Frequency Current Mode Operation by operating the two controllers out-of-phase. n Low Dropout Operation: 100% Duty Cycle Pulse-skipping operation provides high ef ciency at light n True PLL for Frequency Locking or Adjustment loads. 100% duty cycle capability provides low dropout n Selectable Pulse-Skipping/Forced Continuous operation, extending operating time in battery-powered Operation systems. n Auxiliary Winding Regulation n The switching frequency can be programmed up to 750kHz, Internal Soft-Start Circuitry n allowing the use of small surface mount inductors and Power Good Output Voltage Monitor n capacitors. For noise sensitive applications, the LTC3736-2 Output Overvoltage Protection n switching frequency can be externally synchronized from Micropower Shutdown: I = 9A Q n 250kHz to 850kHz. An internal soft-start, which can be Tiny Low Pro le (4mm 4mm) QFN and Narrow lengthened externally, smoothly ramps the output voltage SSOP Packages during start-up. APPLICATIONS The LTC3736-2 is available in the tiny thermally enhanced n One or Two Lithium-Ion Powered Devices (4mm 4mm) QFN and 24-lead narrow SSOP packages. n Notebook and Palmtop Computers, PDAs , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n No R is a trademark of Linear Technology Corporation. All other trademarks are the Portable Instruments SENSE property of their respective owners. Protected by U.S. Patents, including 5481178, n Distributed DC Power Systems 5929620, 6144194, 6580258, 6304066, 6611131, 6498466. TYPICAL APPLICATION Ef ciency and Power Loss High Ef ciency, 2-Phase, Dual Synchronous DC/DC Step-Down Converter vs Load Current (Figure 15 Circuit) V IN 100 10 2.75V TO 9.8V V = 2.5V OUT 10F 95 V IN s 2 + + SENSE1 SENSE2 90 EFFICIENCY 1 TG1 TG2 85 2.2H 2.2H 80 SW1 SW2 LTC3736-2 75 0.1 BG1 BG2 POWER LOSS 70 PGND PGND 65 187k 118k V V OUT1 OUT2 0.01 V V FB1 FB2 2.5V 1.8V 60 I I TH1 TH2 55 220pF 220pF SGND 47F 47F 50 0.001 59k 15k 15k 59k 1 10 100 1000 10000 LOAD CURRENT (mA) 37362 TA01b 37362 TA01a 37362fb 1 EFFICIENCY (%)LTC3736-2 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (V ) ........................ 0.3V to 10V PGOOD ...................................................... 0.3V to 10V IN PLLLPF, RUN/SS, SYNC/FCB, TG1, TG2, BG1, BG2 Peak Output Current (<10s) .... 1A + + TRACK, SENSE1 , SENSE2 , Operating Temperature Range (Note 2) .... 40C to 85C IPRG1, IPRG2 Voltages ................. 0.3V to (V + 0.3V) Storage Temperature Range ................... 65C to 125C IN V , V , I , I Voltages ................. 0.3V to 2.4V Junction Temperature (Note 3) ............................ 125C FB1 FB2 TH1 TH2 SW1, SW2 Voltages ........... 2V to V + 1V or 10V Max Lead Temperature (Soldering, 10 sec) IN (LTC3736EGN-2) ................................................... 300C PIN CONFIGURATION TOP VIEW TOP VIEW + 1 SENSE1 SW1 24 2 PGND IPRG1 23 24 23 22 21 20 19 3 BG1 V 22 FB1 I 1 18 SYNC/FCB TH1 4 SYNC/FCB I 21 TH1 IPRG2 TG1 2 17 5 TG1 IPRG2 20 PLLLPF 3 16 PGND 6 PGND PLLLPF 19 25 SGND 4 15 TG2 7 TG2 SGND 18 V 5 14 RUN/SS IN 8 RUN/SS V 17 IN TRACK 6 13 BG2 9 BG2 TRACK 16 7 8 9 10 11 12 10 PGND V 15 FB2 + 11 SENSE2 I 14 TH2 12 SW2 PGOOD 13 UF PACKAGE GN PACKAGE 24-LEAD (4mm 4mm) PLASTIC QFN 24-LEAD PLASTIC SSOP T = 125C, = 37C/W JMAX JA T = 125C, = 130C/W JMAX JA EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3736-2EGN PBF LTC3736-2EGN TRPBF 24-Lead Plastic SSOP 40C to 85C LTC3736-2EUF PBF LTC3736-2EUF TRPBF 37362 24-Lead (4mm 4mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: